1. Field
This application relates generally to wireless communication, and more specifically but not exclusively to the use of multiple control indications in wireless communication timeslots.
2. Background
Various network topologies may be employed to establish wireless communication. For example, a wide area network, a local area network, or some other type of network may be deployed depending on the desired wireless communication capabilities.
A wireless wide area network is typically a planned deployment within a licensed frequency band. Such a network may be designed to optimize spectral efficiency and quality of service to support a large number of users. A cellular network is one example of a wireless wide area network.
A wireless local area network is often deployed without centralized planning. For example, such a network may be deployed in an ad hoc manner in unlicensed spectrum. Consequently, this type of network may be used to support a single user or a small number of users. A Wi-Fi network is one example of a wireless local area network.
In practice, each of the above networks has various disadvantages due to tradeoffs that may be made to provide a given type of service. For example, due to the complexity of centralized planning, setting up a wireless wide area network may be relatively expensive and time consuming. Hence, such a scheme may not be well suited for “hot spot” deployments. On the other hand, an ad hoc wireless local area network may not achieve the same level of spatial efficiency (bits/unit area) as a planned network. Moreover, to compensate for potential interference between nodes in the network, an ad hoc scheme may employ interference mitigation techniques such as carrier sense multiple access. In practice, however, interference mitigation techniques such as these may lead to poor utilization, limited fairness control, and susceptibility to hidden and exposed nodes.
United States Patent Application Publication No. 2007/0105574 describes a system that may provide various advantages over certain aspects of conventional wide area network and personal area network deployments. In some aspects the system employs timeslot-based communication where multiple wireless nodes in the system may simultaneously transmit and receive during designated timeslots.
Fair-sharing of a wireless channel in the system is facilitated by joint scheduling of a transmission by a transmitter of one node and a receiver of another node through the use of a resource utilization message (“RUM”). Here, a transmitting node may request a set of resources based on knowledge of availability in its neighborhood and a receiving node may grant some or all of the requested channels based on knowledge of availability in its neighborhood. For example, the transmitting nodes may learn of availability by listening to receiving nodes in its vicinity and the receiving node may learn of potential interference by listening to transmitting nodes in its vicinity. In the event the receiving node is affected by interference from neighboring transmitting nodes the receiving node may transmit a RUM in an attempt to cause the neighboring transmitting nodes to stop their interfering transmissions. According to related aspects, RUMs may be weighted to indicate not only that a receiving node is disadvantaged (e.g., due to the interference it sees while receiving) and desires a collision avoidance mode of transmission, but also the degree to which the receiving node is disadvantaged.
A transmitting node that receives a RUM may utilize the fact that it has received a RUM, as well as the weight thereof, to determine an appropriate response. For example, the transmitting node may elect to abstain from transmitting, it may reduce its transmit power during one or more designated timeslots, or it may ignore the RUM for instance if it has received a RUM from its own receiver that indicates its own receiver is more disadvantaged. The advertisement of weights may thus provide a collision avoidance scheme that is fair to all nodes in the system.